Radiation Damage of Tissues
The extent and progression over time of tissue damage following radiation depends on the amount of radiation (total dose) and the fractionation schedule
(i.e., size of each fraction). Following acute effects, chronic changes may occur which are characterized by a deterioration in the small blood vessels, cells, and fibrosis of tissue. Atrophy and ulceration of soft tissues aggravated by trauma and infection are possible further changes. Surgery in irradiated tissue can prove to be a major problem with poor tissue healing. Radiation injury with impaired healing can occur early after therapy but most often appears 3-4 years after treatment. Following radiation of the breast area it is not uncommon to see progressive chronic degeneration for 10 years or
more.
In bone, blood vessels are also damaged by radiation and is accompanied by death of bone cells. These changes lead to osteonecrosis and porosis.
Whichever tissues suffer, the result is the triad of changes i.e., hypovascularity - hypocellularity - and hypoxia.
Treatment with HBO
Clinical challenges following radiation injury vary widely. These include non-healing ulcers and/or the appearance of sequestrated bone. In the mouth
and face these may be aggravated by irritation from dental appliances or prostheses. At any site surgical efforts to cover deficiencies by skin grafts or reconstruction may be complicated by failure to heal.
Hyperbaric Oxygen Therapy (HBO) was introduced over 20 years ago to improve the chances of successful healing in the presence of radiation effects. It is now widely recognized as an important adjunctive therapy. The willingness of third party payors, including Federal agencies to reimburse for HBO treatment
of tissue and osteoradionecrosis support this view.
Rationale for HBO Therapy
Published reports in peer-reviewedjournals have conclusively documented the efficacy of HBOin reducing the morbidity of radiation injury. Progressive changes in walls of blood vessels in irradiated tissues (proliferative endarteritis) leads to a decline in the delivery of oxygen and nutrients. HBO
provides a cyclic increase in tissue oxygen levels that promotes collagen formation by fibroblasts and capillary ingrowth. These processes allow closure of small defects in irradiated tissue and provide an enhanced vascular bed
for healing. This includes improved healing in the event of surgery, graft or flap placement.
Referring a Patient to Our Service and Preliminary Work-Up
Patient referral can be done by letter or telephone (319-356-8220). Please speak to the HBO therapist and ask for the HBO physician on duty. Patients
remain under the care of the referring physician who assesses efficacy of treatments. No consultation of other physicians is undertaken without prior discussion with the referring physician. When necessary for clarification, third party payors are requested to confirm the intention to reimburse.
Examination of a recent chest x-ray is necessary before HBO therapy to exclude air containing cavities in the chest, e.g., bullae likely to contract
and re-expand during treatment. Contraindications to HBO are unusual and virtually all may be regarded as relative when considering the need and/or urgency for therapy.
Foremost contraindications are acute lung infection, history of acute severe asthma, untreated pneumo-thorax and presence of air containing cavities
such as pneumoencephalus. Chronic pulmonary disease or history of spontaneous pneumothorax must always be identified before HBO therapy.
Other conditions that give rise to concern are repeated episodes of middle ear infection. Ninety percent of awake, cooperative patients can compensate for middle ear pressure changes using simple measures. In those who cannot equalize pressures, myringotomy may be required, but will not be done without the agreement of the referring physician and the otolaryngologist who is requested to perform the procedure.
Seizures are a rare complication of exposure to high levels of oxygen. This risk is minimized by "air breaks" during the treatment. Patients
with seizure disorders must have their seizures adequately controlled before HBO treatment. The risk of an oxygen seizure is increased by heavy ethanol intake which must be avoided. The very rare occurrence of a seizure can be controlled by decreasing the inspired oxygen concentration. It is worth recalling that a seizure in an hyper-oxygenated state is different than a
convulsion breathing room air. The use of anticonfulsants is not needed for most HBO induced seizures.
A history of angina should be sought but rarely poses a problem in HBO therapy. Anxious patients may receive sedation during a treatment.
Claustrophobia is not a significant problem with patients due to our ability to accompany them during the treatment.
Optic neuritis is a rare contraindication. It is however, appropriate to warn patients that myopia may occur following therapy and must
be monitored. This regresses spontaneously over a period of weeks.
The effects of HBO in pregnancy need to be evaluated on a case per case basis.
Features of Our HBO Service
1. Referring physician remains the patient’s physician. He/She also assesses efficacy of treatment by seeking evidence such as the following:
- Inflammation should diminish and wounds assume a noninfected
appearance.
- Increased mucosal covering or regression in ulcer size should occur.
- Decrease in amount of exposed bone which is a sign of healing.
- Improvement in pathological x-ray changes may be recognized.
2. Transcutaneous oxygen measurements may be carried out in affected areas to forecast efficacy of HBO therapy.
3. HBO is done in conjunction with existing treatment.
4. Certified HBO physicians and respiratory therapist in attendance during treatments.
5. A series of photographs of lesions are taken to monitor treatment.
6. The hyperbaric chamber is large enough to accommodate up to six patients comfortably in addition to a therapist, who accompanies patients on all treatments.
7. Our Hyperbaric Medicine Service has experience with over 3500 treatments in the treatment of radiation damaged tissues. Results of healing have been consistently satisfactory.
Typical Treatment Regimes with Minimal Number of Treatments
A standard treatment = 100% oxygen (with air breaks) at 2.4 atmospheres for 90 minutes.
- Prevention of osteonecrosis for tooth extraction in irradiated areas - 20 treatments - extraction - 10 treatments.
- Healing of oro-cutaneous fistula - 30-60 treatments.
- Augmentation of elective-maxillo-facial reconstruction - 20 treatments, surgery - 10 treatments.
- Treatment of osteoradionecrosis of mandible- Marx-Univ. of Miami Protocol - Stages II, III, IIIR - 20 treatments - Surgery - 10 treatments.
- Healing of tissue radionecrosis - areas other than head and neck - 20-60 treatments.
Hyperbaric oxygen is a cost effective adjunctive to other therapy in the above conditions.
If you have questions or would like to refer a patient; Call 319-356-8220 or call UI Hospitals and Clinics information at 319-356-1616. Ask for the Hyperbaric medicial doctor.
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